Dental-engine handpiece-cou pling



(No Model.)

0.5. DAVIS. DENTAL ENGINE HANDPIEGE COUPLING.

Patented Aug.6,1895. I

, UNITED STATES :PATENT ()FFICE.

CHARLESH. DAVIS, OF "WORCESTER, MASSACHUSETTS.

DENTAL-ENGINE H ANDPIECE-COUPLING.

SPECIFICATION forming part of Letters Patent No. 543,854, dated August 6, 1895. Application filed May 13, 1895- Serial No.549,160%. (No model.)

To all whom it may concern.-

Be it known that I, CHARLES H. DAVIS, a citizen of the United States, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented a new and useful Improvement in Dental-Engine Handpiece-Oouplings, of which the following is a specification, reference being had to the accompanying drawings, forming a part of the same, and representing a handpiece-couplin g for dental engines embodying my invention.

Figure 1 of the drawings represents a portion of the flexible shaft and handpiece united by one of my improved couplings, shown in side view. Fig. 2 is a vertical central sectional view of my improved coupling, showing so much of the handpiece and flexible-shaft as is necessary to illustrate the subject-matter herein claimed. .Fig. 3 is a perspective and detached view of the barrel, which is attached to the handpiece and adapted to receive an elastic sleeve. Fig. 4 is a perspective and detached view of the elastic sleeve, which is connected with the flexible shaft and adapted to slide over the barrel shown in Fig. 3. Fig. 5 is a perspective and detached view of the triangular shank, which is connected with the tool-driving spindle. Fig. 6 is an end view of the same, and Fig. 7 is a perspective and detached view of the rotating spindle, which is driven by the flexible shaft, the couplingsleeve in which the spindle is journaled, and the elastic or spring jaws formed upon the end of the driving-spindle and adapted to inclose the triangular shank which is shown in perspective view in Fig. 5.

Similar lettersrefer to similar parts in the different figures.

My invention relates to an improved slipjoint or coupling between the ends of two rotatin g spindles having their axes in alignment and also between the ends of tubular casings inclosing the rotating spindles, and it is especially applicable in forming a slip-joint or coupling connection between a handpiece and the driving-shaft of a dental engine.

Referring to the accompanying drawings, and particularly to Fig. 2 of the drawings, A denotes a portion of the covering of a flexible shaft screwed upon the rear end of a couplingsleeve B, forming a bearing for the rotating spindle C, which is journaled in the sleeve B and held from longitudinal movement by means of a shoulder 0, formed in the spindle O, and a collar 0 attached to the spindle, said shoulder andcollar bearing against the ends of the sleeve.

The rear end of the rotating spindle O is operatively connected with and driven by the flexible shaft, and the forward end of the spindle O is provided with elastic jaws 0 preferably three in number, and their inner faces 0 forming a central chamber adapted to receive an angular shank D, preferably triangular, having its sides D fitting the inner faces 0 of the elastic jaws C The shank D is provided with an internal screw-thread D and is held upon a screwthreaded section E of the spindle E,which is journaled in the handpiece F and operatively connected with the tool in the usual manner in instruments of this class. The shank D has its end beveled or tapered, as at D so it will enter readily between the elastic jaws C and also serve as a wedge to slightly separate the elastic jaws in order to cause the faces 0 of the jaws to pinch against the sides D of v the shank and produce a tight fit between the jaws and shank. The handpiece F is screwthreaded at F to receive a barrel G, which is reduced in size at G, forming a shoulder G and having at the base of the shoulder G a shallow annular groove or channel G The end of the barrel G is slightly tapered upon its outer surface, as at G, to enable it to readily enter within a sleeve H, which is screwed upon the front end of the coupling-sleeve B.

The sleeve H is split at H',forming elastic sections H provided at their free ends with a slightly-raised rib H adapted to enter the shallow groove G in the barrel G. The barrel G and the sleeve H form tubular extensions of the handpiece F and flexible shaft A,

which overlap each other, forming a telescopic 7 joint as the shank D is carried between the elastic jaws G The outer diameter of the reduced section G of the barrelG through- -out about half its length from the shoulder G is preferably made slightly larger than the interior diameter of the elastic sections H, so that when the two parts are united the elastic sections H will be slightly separated and made to pinch upon the outer surface of the section G, so as to produce a tight fit and allow the elasticity of the sections H to coinpensate for any wear between the surfaces in contact, and also to produce sufficientfrictional resistance between the section G and the elastic sections 11 to resist the rotation of the barrel G within the sleeve H. As the tapered end G of the barrel is entered between the free ends of the elastic sections II they will be crowded apart until the ends of the sections 11 abut against the shoulder G when the ribs 1-1 will snap into an annular groove G locking the two parts together. The inner edge of the ribs H and the corresponding opposing wall of the shallow groove G are made slightly beveled in order to cause the sections H to be crowded outward when sufficient force is applied to draw the barrel G out of the sleeve II.

When the handpiece and flexible shaft are coupled together with my improved coupling, the ends of the sections H are brought against the shoulder G of the barrel G in order to cause the ribs H to engage the groove G but as the portion of the spindle E which projects beyond the handpiece may vary in length in different handpieces I make the sides D of the shank D of sufiicient length to allow for such variation in the handpieces, causing the shank D to enter farther between the elastic jaws C by an increase in the length of the spindle E.

By the above-described construction I secure a clutching device between the two spindles O and E by means of a shank D held concentrically with the spindle E and entering a central chamber between the elastic jaws C causing the shank D to be rotated by the contact of the faces C of the spindle C with the sides D of the shank.

Each of the jaws C is capable of yielding to accommodate any error of alignment between the jaws and the shank D, and when the two are engaged the jaws are slightly wedged apart by the action of the tapering end G so the elasticity of the jaws serves to hold the faces D in close contact with the sides D of the shank, and the two parts of the coupling are held from separation while in ordinary rise by the elastic sections 11 of the sleeve, which hold the ribs 11 in engagement with the groove G thereby doing awa with a separate latching device.

It will be observed that both jointsviz., that between the spindles C and Eand that between the inclo'sing casings, consisting of the sleeve H and barrel Gare telescopic joints, comprising a male and female part, and that one half of each joint is made elastic, so as to be expanded byits engagement with the other half of the joint, so that any variation in the alignment of the several parts is provided for and tight fit is secured between all the surfaces in contact.

What I claim as my invention, and desire to secure by Letters Patent, is

1. In a coupling for dental engines, the combination of the barrel G provided with an annular groove G, and an inclosing split sleeve having elastic sections 11, and ribs ll adapted to engage said annular groove G substantially as described.

2. In a coupling for dental engines, the combination of the rotating spindle (J provided with elastic jaws C having faces C forming a central chamber adapted to receive an angular shank, a spindle E and an angular shank D having sides D and a tapered end D and carried by said spindle and arranged to enter said elastic jaws, substantially as described.

3. Acouplingfordentalenginehand-pieces comprising a two-part spindle having their axes in alignment and detachably united by a telescopicjoint, and a two-part casing,wherein said spindle is journaled, also detachably united by a telescopic joint, said joints being of such construction that one part thereof is elastic and capable of expansion by the entry therein of the other part, whereby the same are held in place and provision is made for variation in alignment of the parts, substantially as described.

CHARLES H. DAVIS.

In presence of- RUFUS B. FOWLER, EMMA Knsrna. 

